Control of parameters in a global optical controller

ABSTRACT

An optical network system having a global controller capable of controlling all the elements of the network. The controller receives performance data from each optical network element and calculates a performance value for each channel transmitting through the system. The controller then isolates the channel with the minimum performance value and tests possible changes in network element parameters to find a change which would increase this performance value. Once such a change is found, it is implemented and the system is reoptimized.

FIELD OF THE INVENTION

[0001] The present invention relates to optical networks and, morespecifically to optical networks controlled by a single controller.

BACKGROUND TO THE INVENTION

[0002] The future of telecommunications is in optical networks. Opticalchannels, especially with DWDM (dense wavelength division multiplexing),can carry more data, be less error prone, and in the long run be cheaperthan existing copper wire transmission links. For long haul networks,such as transoceanic links, the optimum performance of the network wouldnot only be advantageous but be more profitable to the network operatoras well. However, the optimisation of such networks is, to say theleast, difficult. Generally, such networks are optimised and theninstalled in environments that render servicing such networks if notimpossible, then inconvenient. These environments, such as the floor ofthe Atlantic Ocean, therefore require a self-regulating andself-optimising network. Not only that, but such constraints wouldrequire that adding or subtracting channel capacity, when required, mustbe relatively easier than laying down a new network.

[0003] Furthermore, the aging of optical elements in the network willdegrade the performance of the network. Changes in the environment wherethe network is installed may, from time to time, also affect networkperformance. All of these and other factors contribute to the eventualloss of effectiveness of the initial system optimization. It should alsobe noted that, after the initial system installation, the addition ordeletion of transmission capacity may be desired.

[0004] A further difficulty to optimising such a network, apart from thephysical impediments involved in accessing equipment underneath theocean, is the need to manage and optimise hundreds of differentparameters involved. Each piece of equipment in the network affects thesignals routed through it and each parameter for that piece of equipmentaffects signals differently.

[0005] Based on the above, there is therefore a need for an opticalnetwork system which would be suitable for long haul installations.Ideally, the system should be self optimizing and be able to manage,optimise, and control the different parts of the network. Furthermore,such a system should be upgradable in that extra channel capacity can beadded with relative ease.

SUMMARY OF THE INVENTION

[0006] The present invention meets the above need by providing anoptical network system having a global controller capable of controllingall the elements of the network. The controller receives performancedata from each optical network element and calculates a performancevalue for each channel transmitting through the system. The controllerthen isolates the channel with the minimum performance value and testspossible changes in network element parameters to find a change whichwould increase this performance value. Once such a change is found, itis implemented and the system is reoptimized.

[0007] In a first aspect, the present invention provides an opticaltransmission system for transmitting a plurality of optical signals,said system comprising:

[0008] a plurality of transmitter modules each producing at least oneoptical signal;

[0009] a multiplexer module for multiplexing said plurality of opticalsignals on to a single optical transmitting medium, said multiplexerreceiving said plurality of optical signals from said transmittermodules;

[0010] a plurality of receiver modules each receiver module receiving atleast one optical signal;

[0011] a plurality of optical network elements, said elements beingpositioned between said multiplexer module and at least one of saidreceiver modules; and

[0012] a global controller module for controlling performancecharacteristics and functions of system elements chosen from the groupcomprising:

[0013] said transmitter modules;

[0014] said multiplexer modules;

[0015] said receiver modules; and

[0016] said optical network elements

[0017] wherein

[0018] said global controller module receives data from at least one ofsaid system elements; and

[0019] said global controller continuously optimizes said system bychanging said characteristics and functions of said system elementsbased on said data.

[0020] In a second aspect, the present invention provides an opticaltransmission system for transmitting at least one optical signal from atransmitting end to a receiving end, said system comprising:

[0021] at least one transmitter module at the transmitting end, said atleast one transmitter module transmitting said at least one opticalsignal;

[0022] at least one receiver module at the receiving end, said at leastone receiver module receiving said at least one optical signal;

[0023] a plurality of optical network elements between said at least onetransmitter module and said at least one receiver module, at least oneof said elements being a receiving element receiving said at least oneoptical signal from said at least one transmitter module, at least oneof said elements being a transmitting element transmitting said at leastone optical signal to said at least one receiver module; and

[0024] a controller module controlling said plurality of optical networkelements wherein said controller receives data from said optical networkelements and optimizes the performance of said transmission system bycontinuously modifying performance characteristics of said networkelements based on said data.

[0025] In a third aspect, the present invention provides a method ofoptimizing the performance of an optical transmission system having aglobal controller controlling a plurality of optical network elements,said method comprising;

[0026] a) gathering performance data from at least two said opticalnetwork elements;

[0027] b) calculating a system performance value based on saidperformance data of multiple optical signals;

[0028] c) momentarily changing multiple parameters of said system;

[0029] d) in the event a specific momentary change increases said systemperformance value, implementing a corresponding specific change in saidparameters; and

[0030] e) repeating steps a)-d) after implementing a change in saidparameters.

[0031] In a fourth aspect, the present invention provides a method ofoptimizing an optical communications system having multiple componentsand multiple controllable parameters, the method comprising:

[0032] a) choosing at least one of the multiple parameters to test basedon a history of results of previous tests;

[0033] b) temporarily changing the chosen at least one parameter by afirst predetermined amount;

[0034] c) determining an effect of the change of step b) on theperformance of the system;

[0035] d) determining which action is to be taken relative to the chosenat least one parameter based on the history of results of previoustests, the action being chosen from a group comprising:

[0036] increasing the chosen at least one parameter;

[0037] decreasing the chosen at least one parameter; and

[0038] leaving the chosen at least one parameter at its current setting

[0039] In a fifth aspect, the present invention provides a method ofoptimizing an optical communications system having multiple componentsand multiple controllable parameters, said controllable parametersaffecting at least one transmission channel in said communicationssystem, the method comprising:

[0040] a) temporarily increasing a controllable test parameter by afirst predetermined amount from a base setting, said test parameterbeing one of said controllable parameters;

[0041] b) determining an effect of the increase of step a) on theperformance of the system;

[0042] c) temporarily decreasing the controllable test parameter by asecond predetermined amount from the base setting;

[0043] d) determining an effect of the decrease of step c) on theperformance of the system;

[0044] e) determining if said test parameter is to be increased ordecreased based at least on said effects determined in steps b) and d);

[0045] f) implementing an increase or a decrease in said test parameterbased on results of step e); and

[0046] g) repeating steps a)-f) using the increased or decreased testparameter as a new base.

[0047] In a sixth aspect, the present invention provides an optimizationsystem for optimizing an optical communications system, saidcommunications system having multiple components and multiplecontrollable parameters, the optimization system comprising:

[0048] means for temporarily increasing at least one of saidcontrollable parameters from a base setting;

[0049] means for temporarily decreasing at least one of saidcontrollable parameters from a base setting;

[0050] means for determining if an increase or a decrease in said atleast one of said controllable parameters improves a performancemeasurement of said communications system; and

[0051] means for implementing an increase or a decrease in said at leastone of said controllable parameters such that said at least one of saidcontrollable parameters is changed to form a new base setting.

[0052] In a seventh aspect the present invention provides, an article ofmanufacture comprising:

[0053] a computer readable and executable code, said code comprisingcomputer instructions for optimizing an optical communications systemhaving multiple components and multiple controllable parameters, saidcontrollable parameters affecting at least one transmission channel insaid communications system, the instructions comprising:

[0054] a) temporarily increasing a controllable test parameter by afirst predetermined amount from a base setting, said test parameterbeing one of said controllable parameters;

[0055] b) determining an effect of the increase of step a) on theperformance of the system;

[0056] c) temporarily decreasing the controllable test parameter by asecond predetermined amount from the base setting;

[0057] d) determining an effect of the decrease of step c) on theperformance of the system;

[0058] e) determining if said test parameter is to be increased ordecreased based at least on said effects determined in steps b) and d);

[0059] f) implementing an increase or a decrease in said test parameterbased on results of step e); and

[0060] g) repeating steps a)-f) using the increased or decreased testparameter as a new base.

[0061] In an eighth aspect, the present invention provides a method ofactivating additional transmission capacity in an optical communicationssystem, said additional capacity comprising at least one incomingoptical channel, said method comprising:

[0062] a) determining if operating conditions in said communicationssystem are conducive to an addition of an incoming optical channel;

[0063] b) if operating conditions are conducive to a channel addition,increasing a power level of said incoming channel; and

[0064] c) increasing a contribution of said incoming channel to anoverall system performance measurement.

[0065] In a ninth aspect, the present invention provides an article ofmanufacture comprising:

[0066] computer readable media containing computer readable andexecutable code comprising instructions for a method of activatingadditional transmission capacity in a optical communications system,said additional capacity comprising at least one incoming opticalchannel, said method comprising:

[0067] a) determining if operating conditions in said communicationssystem are conducive to an addition of an incoming optical channel;

[0068] b) if operating conditions are conducive to a channel addition,increasing a power level of said incoming channel;

[0069] c) a contribution of said incoming channel to an overall systemperformance measurement.

[0070] In a tenth aspect, the present invention provides a method ofdeactivating transmission capacity in an optical communications system,said transmission capacity comprising at least one optical channel, saidmethod comprising:

[0071] a) determining if operating conditions are conducive to adeactivation of an optical channel;

[0072] b) if conditions are conducive to a deactivation of an opticalchannel, decreasing a contribution of an outgoing channel to an overallsystem performance measurement; and

[0073] c) decreasing a power level of said outgoing channel.

[0074] In an eleventh aspect, the present invention provides an articleof manufacture comprising: computer readable media containing computerreadable and executable code comprising instructions for deactivatingtransmission capacity in an optical communications system, saidtransmission capacity comprising at least one optical channel, saidinstructions comprising:

[0075] a) determining if operating conditions are conducive to adeactivation of an optical channel;

[0076] b) if conditions are conducive to a deactivation of an opticalchannel, decreasing a contribution of an outgoing channel to an overallsystem performance measurement; and

[0077] c) decreasing a power level of said outgoing channel.

[0078] In a twelfth aspect, the present invention provides a method ofactivating additional transmission capacity in an optical communicationssystem, said additional capacity comprising at least one incomingoptical channel, said method comprising:

[0079] a) determining parameter settings for equipment saidcommunications system for adding one incoming channel;

[0080] b) determining if operating conditions in said communicationssystem are conducive to an addition of an incoming optical channel;

[0081] c) activating said incoming channel if operating conditions areconducive to a channel addition;

[0082] d) increasing a power level of said incoming channel; and

[0083] e) optimizing the communications system while said power level isbeing increased.

[0084] In a thirteenth aspect, the present invention provides a methodof optimizing an optical communications system after adding additionaltransmission capacity, said method comprising:

[0085] a) increasing a contribution of an incoming channel to a overallsystem performance measurement;

[0086] b) experimenting with parameters of said system to increase saidsystem performance measurement; and

[0087] c) repeating steps a)-b) until said incoming channel is a fullcomponent of said system performance measurement.

[0088] In a fourteenth aspect the present invention provides a method ofassessing an overall performance of an optical communications system,said system having multiple parameters and multiple channels, the methodcomprising:

[0089] a) gathering performance data for said multiple channels;

[0090] b) calculating a cost function based on said performance data;and

[0091] c) determining if said cost function exceeds a predeterminedthreshold.

[0092] In a fifteenth aspect the present invention provides a method ofincreasing performance of an optical communications network havingmultiple channels and multiple adjustable parameters, the methodcomprising:

[0093] a) gathering performance data measurements for a plurality ofsaid multiple channels;

[0094] b) determining an overall performance measurement for said systembased on said performance data measurements; and

[0095] c) adjusting selected adjustable parameters to improve saidoverall performance measurement for said system.

[0096] In a sixteenth aspect the present invention provides a method ofdeactivating transmission capacity in an optical communications systems,said transmission capacity comprising at least one outgoing opticalchannel, said method comprising:

[0097] a) determining if operating conditions are conducive to adeactivation of an optical channel;

[0098] b) if conditions are conducive to a deactivation of an opticalchannel, decreasing a power level of said outgoing channel; and

[0099] c) optimizing said communication system.

[0100] In a seventeenth aspect the present invention provides a methodof deactivating transmission capacity in an optical communicationssystems, said transmission capacity comprising at least one outgoingoptical channel, said method comprising:

[0101] a) determining if operating conditions are conducive to adeactivation of an optical channel;

[0102] b) if conditions are conducive to a deactivation of an opticalchannel, decreasing a contribution of an outgoing channel to an overallsystem performance measurement;

[0103] c) of optimizing said communication system.

DETAILED DESCRIPTION OF THE DRAWINGS

[0104] A better understanding of the invention may be obtained byreading the detailed description of the invention below, in conjunctionwith the following drawings, in which:

[0105]FIG. 1 is a block diagram of an optical network;

[0106]FIG. 2 is a block diagram of a possible control scheme for theoptical network of FIG. 1;

[0107]FIG. 3 is a block diagram of an alternative control scheme for theoptical network of FIG. 1;

[0108]FIG. 4 is a block diagram of yet another control scheme for thenetwork of FIG. 1 which increases the level of control that the globalcontroller has over the network elements;

[0109]FIG. 5 is block diagram of a further control scheme for thenetwork of FIG. 1 that is a hybrid of the other control schemesillustrated previously;

[0110]FIG. 6 is a block diagram illustrating the steps in the continuousoptimization process according to one aspect of the invention;

[0111]FIG. 7 is a flowchart detailing the steps in the channel additionprocess; and

[0112]FIG. 8 is a flowchart detailing the steps in the channel deletionprocess.

DETAILED DESCRIPTION

[0113] Referring to FIG. 1, a block diagram of an optical networkaccording to the invention is illustrated. A number of transmittermodules 10 transmit multiple channels 20 to an optical multiplexermodule 30. The multiplexer multiplexes the channels 20 on to a singleoptical transmission medium (normally an optical fiber) which is fed toan optical amplifier module 40A. For long haul installations, multipleoptical amplifier modules 40B, 40C amplify the multiplexed signalsbefore finally delivering them to an optical demultiplexer module 50.The demultiplexer 50 then demultiplexes the signals into multiplechannels 60 for delivery to multiple receiver modules 70. A globaloptical controller 80 communicates to each of the network elements inthe network through a communications path 90.

[0114] As can be seen, each of the network element modules has a localcontroller 100 which is able to control the network elements' operatingcharacteristics. The global controller is able to communicate with thelocal controller 100 not only for data gathering but also forcontrolling each network element module.

[0115] To clarify the function of the network illustrated in FIG. 1, theglobal controller collects data relating to network performance fromeach of the element modules. The global controller then collates thisdata to arrive at a performance value for each of the multiple signals.The performance value is a number which indicates whether the signal isbeing transmitted properly and efficiently. The signal having the lowestperformance value is then found and parameters which affect thisperformance value is determined. The controller carries out multiplepredetermined experiments which affect this lowest performance value.The experiments are in the form of changing specific parameters bypredetermined amounts. The effect of this experiment on the performancevalue is then logged and used to determine which experiment yielded thebest results in terms of increasing this lowest performance value. Oncethe most successful experiment is found, the measures taken for thatexperiment are then applied and the optimisation is begun anew,hopefully with a new signal having a new lowest performance value.

[0116] The optimisation executed by the global controller is awell-known problem in the field of optimization. The search forparameters which maximize a minimum value is known as the minimaxproblem and analytical methods exist to assist in finding such asolution. However, given the nature of such problems and their erstwhilesolutions, it is possible that a number of “solutions” may arise amongwhich the controller may get trapped. To avoid such a possibility,providing weights to specific parameters in the equations, with theweights decaying per experiment, gives an element of randomness whichshould avoid such solutions. A more detailed discussion and explanationof such an optimisation scheme is set later in this document.

[0117] Another possible optimization scheme is to use cost functions.These cost functions measure the overall performance of the system andare based on measurements of performance of the system elements or ofthe system channels. To optimize using cost functions, trade-offs may bemade between different components or elements. By reducing theperformance of one element, an increased by cost function, may beobtained. On, by reducing a specific parameter, one element may bedetrimentally affected while another may be advantageous affected toresult in an improvement in overall performance. This optimizationscheme is also explained and discussed in detail below.

[0118] Returning to FIG. 1, it should be noted that, while the networkelements illustrated are only optical amplifiers, other elements such asoptical cross-connects, optical filters, diffusion (dispersion)compensation modules, add/drop multiplexers, lasers, pulse generators,modulators, polarization and delay devices, Raman amplifiers, and gainflattening filter can be used as well.

[0119] Control Scheme

[0120] As noted above, the global controller receives data from thenetwork element modules and also controls these same modules. The globalcontroller accesses data by querying each module and receives data inreturn. For control, the global controller sends a control message tothe relevant network element module setting the modules parameters. Oncethe module receives this message, it sets the proper parameters andsends an acknowledgement back to the global controller.

[0121] Referring to FIG. 2, a possible control scheme is illustrated ina block diagram. The global controller 80 communicates with localcontroller 100. Each local controller 100 directly controls multiplenetwork element modules. This scheme therefore envisions that globalcontroller messages and queries are to be passed, interpreted, andimplemented by each local controller 100 for the network element modulesunder its control. With this scheme, the global controller cannotdirectly access a network element without direct intervention from thelocal controller.

[0122] Referring to FIG. 3, another control scheme is illustrated. Inthis scheme, the global controller's messages and queries are passeddirectly to each network element. The global controller thus can sendcontrol messages directly to a network element. The element can thenimplement or respond to the message accordingly. Each message or queryis sent to the local controller by the global controller. The message orquery is then re-routed to the relevant network element. The localcontroller thus acts simply as a redirection agent for each elementmodule.

[0123] The control scheme is FIG. 4, on the other hand, furtherincreases the level of control that the global controller has over thenetwork elements. In FIG. 4, the global controller sends messagesdirectly to the network element without any intervention from the localcontroller. The network elements then receive the messages and implementor respond to them accordingly.

[0124] The control scheme of FIG. 5 is a hybrid of the other controlschemes discussed. The global controller sends messages only to certainlocal controllers and these messages are re-routed to the networkelement. The local controllers, which receive messages directly, mayredirect global messages to network elements in other modules. Whileseemingly counterintuitive, the scheme does reduce the amount ofconnection to the global controller. With this scheme, the messages arereceived by the network element and are directly implemented orresponded to.

[0125] While the schemes presented above offer different options withregard to the number of connections and the level of control for theglobal controller, any of the above can be used for the network.

[0126] It should be noted that, to assist in the control scheme, eachnetwork element would have its own unique address in the network. Withthis, the global controller can send messages to a network element bymerely using that element's unique address. Depending on the controlscheme used, the address resolution may be implemented and carried outby the local controller or address resolution may not even by needed(see discussion above for control scheme in FIG. 4).

[0127] To further facilitate understanding of the control mechanism forthe network elements, the control messages emanating from the globalcontroller to the network element may have the form of a requestmessage. The request message requests something of the network element,whether data or that an action be performed by the network element. Sucha request message would have the following fields:

[0128] Message number;

[0129] Source address;

[0130] Destination address;

[0131] Action requested; and

[0132] Parameters of action requested.

[0133] The action requested by the global controller can be one of twoactions: set a parameter to a desired target or measure a desiredparameter. For the set command, the following fields are required toproperly set the parameter:

[0134] Parameter: the identity of the parameter to be set;

[0135] Target: the desired target value for the parameter to be set;

[0136] Timeout duration: the allotted time to set the parameter to thetarget value.

[0137] For a measurement message, the global controller is requestingthat the network element measure a certain parameter. The measurementmessage thus can have the following fields:

[0138] Parameter: the identity of the parameter to be measured; and

[0139] Duration: the duration of the measurement if applicable.

[0140] In response to a message from the global controller, the networkelement sends a response message back to the global controller. Theresponse message would have the following fields:

[0141] Message Number;

[0142] Destination Address;

[0143] Source Address;

[0144] Result of Request;

[0145] Result Field;

[0146] Reason.

[0147] The result field would have subfields that indicate the resultsof the request. Thus, if the request was a set request, the fields ofthe results could be the following fields:

[0148] Parameter: Identity of the parameter which the global controllerrequested to be set;

[0149] Achieved Target: The actual setting of the parameter. This can berequested setting or a setting approximating the requested setting.

[0150] If on the other hand, the network element timed out, then theresult will be a null—the request was not achieved. Under the reasonfield of the response message, the reason for not achieving the requestwould be entered. The reason can be a timeout, element equipment fault,an improper request, or element equipment not available (unknowndestination address).

[0151] If the global controller had requested a measurement to be taken(request for data), then the response message would have the followingfields for the results field:

[0152] Parameter: identity of the parameter measured;

[0153] Measured Value: the value of the requested parameter;

[0154] Duration of Measurement: time duration of the measurement (ifapplicable or if requested by the global controller).

[0155] Again, if the measurement could not be accomplished, then theresult field be a null. Under the reason field the cause of the nonmeasurement can be explained.

[0156] While the above control scheme can be used to test the system forthe effects of changing specific parameters, this method can be quitetedious. In this scheme, the global controller would choose at least oneparameter to be tested. This parameter(s) is then set to a predeterminedtest value and then the effects of this setting are measured. Theparameter(s) are then reset to their previous setting and a new testvalue is tested. Once all the test/measure/reset sequences are done forthe test values, the global controller determines which test settingoffers the best performance value based on the results. This chosensetting is then re-implemented and the testing begins anew using the newsetting as the initial base setting.

[0157] To reduce the amount of traffic between the global controller andthe network elements, an alternative would be to implement a perturbfunction in each element. This perturb function would allow each elementto change at least one specific parameter by a certain amount for aspecific amount of time and measure the changes resulting from thetemporary change. Once the specific amount of time has passed, theparameter's setting is returned to its original value. The globalcontroller thus provides the network element with values required forthe perturbation to be implemented and the network element responds witha measured response. Thus, in addition to the set and measure commands,a perturb command can be added. Under the action requested field of therequest message, the entry would be perturb. The parameters of theaction required would be: Parameters: the identity of the parameter tobe perturbed; Target: the target value to which the parameter is to bemomentarily set to. As an alternative, this can be a step value or avalue by which the parameter setting can be increased or decreasedrather than a specific parameter setting; Time for the amount of timethe parameter Perturbation: setting is to be held at the settingindicated by the target field; and Duration: the duration of themeasurement to be taken.

[0158] As noted above, when the perturb command is received by thenetwork element, the parameter identified is set to the desired settingfor the desired amount of time and the resulting effect on theperformance value is measured for the set duration.

[0159] Optimization

[0160] To optimize the system described above, manual optimization canbe used. However, the passage of time and changing operating conditionswill eventually render this manual optimization useless. A continuousoptimization method is therefore required to account for changingconditions and for wear and tear. Continuous optimization can allow forchanging traffic conditions and changing system priorities. Thecontinuous optimization optimizes by experimenting with the differentparameters of the optical system. A cost function that takes intoaccount all the performance measurements of each element in the systemis used as the overall performance measurement. From a base setting,each chosen parameter is increased by a predetermined amount and theeffects of this perturbation on the cost function is evaluated. Eachchosen parameter is then returned to its base setting. These chosenparameters are then decreased by another predetermined amount and theeffects of this new setting on the cost function are evaluated. Based onhow the different costs function compare to one another, each chosenparameter is either increased, decreased, or kept at the same setting.This new base setting will thus now be the basis for another set ofperturbation experiments.

[0161] It should be noted that the optimization process is continuous.This means that optimization is carried out on the system as long as thesystem operates. The optimization process can be carried outperiodically, as in once every hour or once every few days. However, theoptimization process can also be carried out consecutively in that afterone optimization terminates another is automatically started.

[0162] The above method also employs multiple weighting factors whichcan be adjusted to lend more importance to different factors. Also, thecost function can be based on a number of different possible factors. Inone implementation, the cost function is based on channel BER or biterror rate. However, this need not be the only basis. Channel noise,channel throughput, and other measurements can form the basis of thecost function. In addition to these alternatives, the history ofprevious decisions taken can also be used in deciding whether toincrease a parameter, decrease a parameter or leave the parameter at itscurrent setting.

[0163] In one implementation, the cost functions is defined as${FC} = {\sum\limits_{i = 1}^{Nc}{{Wci}\left( {\Delta \quad Q} \right)}^{\alpha}}$where ${\Delta \quad Q} = \begin{Bmatrix}{{\left( {{Qth} - {Qi}} \right)\quad {if}\quad {Qi}} < {Qth}} \\{0,\quad {{{if}\quad {Qi}} \geq {Qth}}}\end{Bmatrix}$

[0164] Nc=number of channels in the system

[0165] Wc=channel weighting coefficient vector

Wc=[Wc₁, Wc₂, . . . Wc_(Wc)]

[0166] Qth=Threshold value for Q, fixed as a predefined constant or as avariable to be adaptively adjusted during system optimization

[0167] Qi=Q value for channel i

[0168] ∝=power factor which may be adjusted to control the behaviour ofthe cost function and should be greater than zero.

[0169] In the above cost function the Q value is related to the BER (biterror rate) for a channel. However, Q need not be related to the BER. Aslong as Q is a measurement of a channel's signal quality where a lower Qis desirable, then the above cost function will be useful. Other costfunctions are possible as long as these cost functions account for allthe channels in the system and the final result of the cost function isa measurement of the performance of the whole system.

[0170] It should be kept in mind that the ultimate goal of theoptimization is, as noted above, to maximize the minimal Q. The costfunction given above does not take into consideration Q values that areabove a certain threshold. Only Q values below Qth are used and these Qvalues are ones targeted for maximizing.

[0171] Once the cost function for the base setting is found, theoptimization procedure must choose which parameters are to beexperimented with, or targeted. This is done by calculating the sortingfunction for each parameter. A parameter's sorting function value willbe an indication of that parameter's “importance” in adjusting theeffectiveness of the optimization. These sorting function parameters arethen ranked to determine which parameters are to targeted.

[0172] The sorting function for each function can be defined as:

Fc ₁=|(FD+)₁−(FDo)₁|+|(FDo)₁−(FD−)₁|

[0173] for parameter i FD+, FDo, and FD− are decision functions based ona history of previous adjustment decisions and current tests based onstated experiment methods for that parameter. These decision functionswill be described in more detail below.

[0174] Once each parameter's sorting function value is calculated, allof the sorting function values are ranked in descending order. Theseranked sorting function values are then mapped on to a matrix with Nsrows and (N/Ns) columns for N parameters. From the resulting matrix, onecan determine which parameters are to be targeted. Each row in thematrix is a sorting set and the first Nst columns from the leftdetermine the targeted parameters, with Nst being a value between 1 and(N/Ns). Therefore, if the following are the sorting function values forthe following parameters,

[0175] P_(A)(FS)=0.2 P_(I)(FS)=0.45 P_(Q)(FS)=0.38

[0176] P_(B)(FS)=0.82 P_(J)(FS)=0.57 P_(R)(FS)=0.93

[0177] P_(C)(FS)=0.9 P_(K)(FS)=0.73 P_(S)(FS)=0.42

[0178] P_(D)(FS)=0.11 P_(L)(FS)=0.25 P_(T)(FS)=0.27

[0179] P_(E)(FS)=0.22 P_(M)(FS)=0.67

[0180] P_(F)(FS)=0.15 P_(N)(FS)=0.58

[0181] P_(G)(FS)=0.72 P_(O)(FS)=0.49

[0182] P_(H)(FS)=0.33 P_(P)(FS)=0.52

[0183] then a sorted list with the largest sorting function value infront will be:.

[0184] P_(R)=0.93

[0185] P_(C)=0.9

[0186] P_(B)=0.82

[0187] P_(K)=0.73

[0188] P_(G)=0.72

[0189] P_(M)=0.67

[0190] P_(N)=0.58

[0191] P_(J)=0.57

[0192] P_(P)=0.52

[0193] P_(O)=0.49

[0194] P_(I)=0.45

[0195] P_(S)=0.42

[0196] P_(Q)=0.38

[0197] P_(H)=0.33

[0198] P_(T)=0.27

[0199] P_(L)=0.25

[0200] P_(E)=0.22

[0201] P_(A)=0.2

[0202] P_(F)=0.15

[0203] P_(P)=0.11

[0204] Clearly, the above is for a system with 20 different parameters.The above list can then be placed in a matrix of 5 rows, if 5 sets aredesired, as such: $\left\lbrack \left. \quad\begin{matrix}P_{R} & P_{M} & P_{I} & P_{L} \\P_{C} & P_{N} & P_{S} & P_{E} \\P_{B} & P_{J} & P_{Q} & P_{A} \\P_{K} & P_{P} & P_{H} & P_{F} \\P_{G} & P_{O} & P_{T} & P_{D}\end{matrix} \right\rbrack \right.$

[0205] From this matrix, the first N_(st) rows denote the targetedparameters. Thus, if N_(st)=1, then the targeted parameters are P_(R),P_(C), P_(B), P_(K), and P_(G). These parameters will therefore be theparameters to be perturbed in the experiments. On the other hand, ifN_(st)=2, then the first two rows denote the parameters to beexperimented with.

[0206] By placing the sorting function values in a matrix, it is easierto determine which parameters are to be used in the experiments. As anexample, if the number of parameters to be experimented with are to bein multiples of 5 (5 parameters, 10 parameters, or 15 parameters) thenfrom the matrix above, this can easily be done. The optimizationprocedure need only choose one, two, or three columns to increase thenumber of targeted parameters.

[0207] Once the targeted parameters are chosen, each targeted parameteris, in turn, increased by a predetermined amount. As an example, ifN_(st)=1 and using the matrix above, then the targeted parameter for thefirst set (the parameters in the first row) is P_(R). The “un-sorting”parameters or the parameters in the same set as the targetedparameter(s) but which are not targeted, are each randomly set to adifferent setting. This random new setting is achieved by adding orsubtracting a predetermined value to each of these untargetedparameters. A random new setting is also set for a number of theuntargeted parameters from the other sets. Thus, from the above matrix,the following settings can be set, with the + symbol denoting anincrease in the base setting and the − symbol denoting in the basesetting and a o denoting no change: P_(R) ⁺ P_(N) ⁻ P_(I) ⁺ P_(L) ⁺P_(C) ^(o) P_(N) ⁻ P_(S) ^(o) P_(E) ^(o) P_(B) ^(o) P_(J) ⁺ P_(Q) ⁺P_(A) ⁺ P_(K) ^(o) P_(P) ⁻ P_(H) ^(o) P_(F) ^(o) P_(G) ^(o) P₀ ⁻ P_(T)^(o) P_(D) ⁺

[0208] As can be seen, only the first element in the first column (thetargeted parameters) is given a change. Also, it should be noted thatall the elements in the targeted set (P_(M), P_(I), P_(L)) are eachrandomly adjusted with either a decrease or an increase. Furthermore,parameters which are neither in the targeted set nor in one of thetargeted parameters are randomly chosen and randomly adjusted with adecrease or an increase. If a parameter is not chosen, then no change isapplied.

[0209] After the first experiment, a second similar experiment isexecuted. The procedure is the same except that the targeted parameteris decreased by another predetermined amount from the base setting. Thesettings for the other parameters are kept at the same settings as thefirst experiment. The settings are thus: P_(R) ⁻ P_(M) ⁻ P_(I) ⁺ P_(L) ⁺P_(C) ^(o) P_(N) ⁻ P_(S) ^(o) P_(E) ^(o) P_(B) ^(o) P_(J) ⁺ P_(Q) ⁺P_(A) ⁺ P_(K) ^(o) P_(P) ⁻ P_(H) ^(o) P_(F) ^(o) P_(G) ^(o) P₀ ⁻ P_(T)^(o) P_(D) ⁺

[0210] With these new settings, the cost function is measured andcalculated. The result is then stored and catalogued as being from thedecrease experiment. It should be noted that the above procedure canalso be used if the rows referred to above were columns and vice versa.

[0211] From the above, it should be clear that for each targetedparameter there are 2 experiments and, as a result, for each set ofN_(st) targeted parameters, there will be 2*N_(st) experiments andresults. All of these results are stored and kept along with theprevious results and decisions in previous experiments.

[0212] As a first step in deciding which direction to change aparameter, the cost function record for that parameter is reorganizedinto three subsets—a first subset for previous decisions that increasedthe parameter, a second subset for previous decisions that decreased theparameter, and a third subset for previous decisions that did not changethe parameter. Each subset therefore becomes a decision record or avector of cost function values detailing the final cost function valueafter each decision.

[0213] From each of the above vectors, a ratio is calculated. Theseratios are:${{FR} + (P)} = \frac{\sum\limits_{j = 1}^{N +}\left\lbrack {{{Wdj}(P)}{{Wtj}\left( P_{i} \right)}{{FC}_{j}(P)}} \right.}{\sum\limits_{j = 1}^{N +}\left\lbrack {{{Wdj}(P)}{{Wtj}(P)}} \right\rbrack}$${{FR} - (P)} = \frac{\sum\limits_{j = 1}^{N -}\left\lbrack {{{Wdj}(P)}{{Wtj}\left( P_{i} \right)}{{FC}_{j}(P)}} \right.}{\sum\limits_{j = 1}^{N -}\left\lbrack {{{Wdj}(P)}{{Wtj}(P)}} \right\rbrack}$${{FR0}(P)} = \frac{\sum\limits_{j = 1}^{N0}\left\lbrack {{{Wdj}(P)}{{Wtj}\left( P_{i} \right)}{{FC}_{j}(P)}} \right.}{\sum\limits_{j = 1}^{N0}\left\lbrack {{{Wdj}(P)}{{Wtj}(P)}} \right\rbrack}$

[0214] where

[0215] Wd_(n) is a distance weighting coefficient, the formula for whichis given below;

[0216] Wt_(n) is a time weighting coefficient, the formula for which isgiven below;

[0217] N+ is the total number of times in which the parameter has beenincreased in the decision record;

[0218] N− is the total number of times in which the parameter has beendecreased in the decision record;

[0219] No is the total number of times in which the parameter has notbeen changed in the decision record; and

[0220] FC_(n) is the n^(th) cost function for parameter O in therelevant decision record or decision vector.

[0221] To calculate the distance weighting factor, one of two methodsmay be used. The first method is to consider the projecting distance−Wd_(])(P) is a projection on parameter of the real space distancebetween the base setting of the parameter (also known as the baseposition) and the setting after the perturbation. This can be found bythe following formula:${{Wdj}(P)} = \frac{1}{\left\lbrack {{{\overset{\_}{P} - {Pj}}}^{} + \beta} \right.}$

[0222] where

[0223] {overscore (P)} is the base setting of the parameter in thecurrent experiment;

[0224] P_(]) is the experimental setting of the parameter for thecurrent set. Thus, this value is the increased setting if the weightingfactor is for the increased setting subset. Alternatively, this is thedecreased setting if the weighting factor being calculated is for thedecreased setting subset;

[0225] ζ is a constant between 2 and 3. This constant may be selected tocontrol the system convergence overshoot;

[0226] β is a constant between 1 and 4. β can be used to flatten out theweight near to zero (P−P_(j)), while letting th weighting factor rolloff quickly as (P−P_(])) increases. A smaller β rejects more experimentnoise while a larger β averages more Q measurement noise.

[0227] The second method for calculating the weighting factor involvesdefining the Wd_(j)(P) as the vector distance or as the real spacedistance between the base setting of P and the experimental setting.This can be found using the formula:${{Wdj}(P)} = \frac{1}{\left\lbrack {{\overset{\rightarrow}{PB} - \overset{\rightarrow}{{PP}_{j}}} > { + \beta}} \right\rbrack}$

[0228] where

[0229] BP: Base position of the base setting for P

[0230] PP_(]): the perturbation position of the position after theexperimental setting of the parameter

[0231] and${\overset{\rightarrow}{BP} - \overset{\rightarrow}{{PP}_{j}}} = \left\{ {{\sum\limits_{k = 1}^{N\quad p}{1\overset{\_}{P}\quad k}} - {Pk1}^{}} \right\}^{1/2}$

[0232] ζ and β are as defined above

[0233] N_(p)=the number of parameter dimensions (how many targetedparameters there are)

[0234]Pk=the base setting for parameter k for this experiment

[0235] Pk=the experimental setting for parameter k for this specificexperiment type (if the experiment is of the increased variety, then Pkis the increased setting but if the experiments is of the decreasevariety then Pk is the decreased setting.

[0236] The idea behind the distance weighting is to average or low passfilter the measurement and to put more weight on those experiment whichhave the positions closer to the base settings.

[0237] For the time weighting factor, it is an experimental function andcan be calculated by the formula: ${{Wtj}(P)} = ^{(\frac{- t}{T})}$

[0238] where

[0239] t=time period between the current experiment and theexperiment/decision being considered. This time period can be found by

t=M*Te

[0240] where Te is the time period or duration per experiment and M isthe experiment number from the experiment being considered and thecurrent experiment.

[0241] T is a decay constant which may be hours or days. This constantmay be adjusted by the system itself during operation.

[0242] The time weighting factor weighs down the earlier historyresults. These earlier results may have an undue effect on the currentsystem behaviour due to the system's slow performance drifting withtime.

[0243] Once the ratios have been calculated, the decision functions canbe found. The decision functions are to be the final basis for decidingwhether a parameter is to be increased, decreased or left at its presentsetting. These decision functions are based on at least a portion of thedecision record or the decision vector, the record of the previousdecisions taken for that particular parameter. Of course, the depth ofthe decision record or how far back the decision record goes isdependent on both the system requirement and the resources available tothe system.

[0244] The decision functions are defined for three cases:

[0245] Case 1: Normal

[0246] FD+(P)=FR+(P)+Υ*[FRo(P)−FR−(P)]

[0247] FD−(P)=FR−(P)+Υ*[FRo(P)−FR+(P)]

[0248] FDo(P)=FRo(P)

[0249] Case 2: A positive perturbation of the parameter setting is notfound in the decision record period

[0250] FD+(P)=(1+Υ)*[FRo(P)−FR−(P)]

[0251] FD−(P)=FR−(P)

[0252] FDo(P)=FRo(P)

[0253] Case 3: A negative perturbation of the parameter setting is notfound in the decision record period

[0254] FD+(P)=FR+(P)

[0255] FD−(P)=(1+Υ)*[FRo(P)−FR+(P)]

[0256] FDo(P)=FRo(P)

[0257] In all of the above cases, the following definitions apply:

[0258] Υ is a constant with a value between 0 and 1

[0259] FRo (P), FR−(P), and FR+(P) are the ratio function values forparameter P as defined above.

[0260] It should be noted that the decision record period is the portionof the decision record used in determining the ratio function. The wholedecision record need not be used. Thus, a decision record may contain100 entries but the period used may only be the most recent 20 decision.As can be seen from the above decision functions, if the period in thedecision record is anomalous in that possible changes to the parametersetting are not applied, specific decision functions are calculateddifferently.

[0261] With the decision functions determined, the decision as to thedirection of change in the parameter setting can be taken. This decisionis based on a comparison of the 3 decision functions:

[0262] If FD+(P) is the smallest: Parameter P is increased by onepredetermined step.

[0263] If FD−(P) is the smallest: parameter P is decreased by onepredetermined step.

[0264] If FDo(P) is the smallest: parameter P is left at its basesetting.

[0265] It should be noted that increasing or decreasing or the parameterby one step is simply a matter of resetting the parameter to therelevant experimental setting. This new setting will then become the newbase setting for the next experiment. However, setting the parameter toits experimental setting does not necessarily mean duplicating the otherexperimental settings for the other non-targeted parameters. In theinterests of predictability, it may be more useful to leave thenon-targeted parameters to its own base settings when implementing thedecision concerning the targeted parameters.

[0266] It should also be noted that the Υ constant used in calculatingthe decision functions has a specific function. This constant can beused to assist the system in decision making when there is no experimentfor a parameter in a certain direction. The choice of a value for thisconstant can also be used to speed up system convergence or to preventthe system and its optimization from crossing a specific threshold.

[0267] Once the decision regarding the change in the parameter setting,this decision is implemented. Once implemented, the new setting becomesthe base setting for the next set of experiments.

[0268] While the above process may seem circuitous, given that thesorting function, which determines which parameters are to be targeted,seems to be dependent on the decision function that is calculated onlyin the end, the process is not. The decision function on which thesorting function is based is calculated using the cost function historythat does not include the experiment to be performed. Thus, if thecurrent trial is numbered n, the decision function used in determiningthe sorting function for trial n is calculated on a decision record thatonly includes trials prior to trial n. Trials n−1, n−2, n−3, . . . n−a,a≦n, may be included in this decision record. From this, the targetedparameters are therefore chosen based on the previous history of trials.

[0269] The above process for continuous optimization, a so-calledsteady-state optimization, is summarized in the flowchart of FIG. 6.

[0270] Referring to FIG. 6, the process begins at step 200. This stepinitializes the process and sets a counter n to a value of 1. Step 210is that of starting trial number n.

[0271] Step 220 is that of sorting the multiple controllable targetparameters (in this case there are N target parameters) to determinewhich target parameters are to be examined first. Step 230 is a dualstep—that of executing the experiments and then calculating the costfunction for each experiment. The calculation of the cost function willbe discussed further below. Essentially the cost function reduces to asingle value the overall effect on the system by an experiment. Thus, incalculating the cost function for each experiment, the overall effect ofthat experiment is found, thereby simplifying the comparison betweenexperiments.

[0272] Step 240 is that of weighting the cost function results of step230. This step thus gives different weights to different results. Timeweighting gives more weight or effect to recent experiments and lessweight or effect to older experiments. Distance weighting puts moreweight or effect on experiment results which are closer to the currentsystem setting. Thus, if the current setting for a parameter is Pcurrentand the “distance” between Pcurrent and P₁ is greater than the distancebetween Pcurrent and P₂, with P₁ ad P₂ being parameter settings inprevious experiments, the experiment results using the setting P₂ willbe given more weight. The net effect of the weighting is to give moreweight or effect in the decision making step (step 250) to experimentresults which are not only more recent but whose parameter settings arecloser to the system's current setting. Such a step helps in reducingover time the effect of erroneous decisions or improperly setparameters.

[0273] Step 260 is of actually implementing the decision of step 250.The global controller thus sends out commands to the system elementswith specific settings for specific parameters.

[0274] Step 270 adjusts the settings which will be used for the nextexperiment. Among other things, the database of previous experimentresults is to be updated and the starting point for the next experimentis to be adjusted to the current parameter settings based on thedecisions made in step 250.

[0275] Step 280 increments the counter n and, as can be seen from FIG.6, the process begins anew with step 210.

[0276] While the above optimization procedure uses multiple functions,such as the sorting, ratio, and decision functions, to determine whichparameters are to be targeted, an alternative method takes into accountparameters which affect multiple channels.

[0277] The method outlined below does not use any of the functionsdiscussed above but follows the same concept of experimenting withparameters to optimize the overall system. The parameters for which themethod below will apply will be parameters which clearly affect multiplechannels. These include all line amplifier parameters, all Ramanparameters, multiplexer current, transmit wavelengths, and the 4 channelEDFA (erbium doped fiber amplifier) gain at the demultiplexer. It shouldbe noted that the experimental procedure is the same for this process asfor the procedure above. Each parameter is randomly perturbed (increasedor decreased) by a set amount and, while at that setting, performancemeasurements are taken. The measurements are manipulated and, based on ahistory of previous measurements or decisions, the parameter isincreased or decreased.

[0278] Essentially, the method determines a ratio for each parameterand, based on that ratio, the parameter is increased or decreased. On atheoretical level, the ratio R(p) for each parameter is found by usingthe following functions:${R(p)} = {\sum\limits_{i = 1}^{Nch}{\frac{{Weight}\quad \left( {p,{ch}} \right){{Av}\left\lbrack {{CFclope}\left( {p,{ch}} \right)} \right.}}{\left( {\ln \left( {aQ}_{ch} \right)} \right)^{2}}\quad {with}}}$${{Weight}\quad \left( {p,{ch}} \right)} = {\frac{{{Av}\left\lbrack {{CFslope}\left( {p,{ch}} \right)} \right\rbrack}}{\zeta^{2}{{Qn}\left( {p,{ch}} \right)}}\quad {and}}$${{Av}\left\lbrack {{CFslope}\left( {p,{ch}} \right)} \right\rbrack} = {\frac{1}{N}{\sum\limits_{j = 1}^{N}{{\ln \left( \frac{{{Qch}\left( {p -} \right)},j}{{{Qch}\left( {p +} \right)},j} \right)}\quad {and}}}}$${^{2}{{Qn}\left( {p,{ch}} \right)}} = {\frac{1}{N\left( {N - 1} \right)}{\sum\limits_{j = 1}^{N}\left\lbrack {{\ln \left( \frac{{{Qch}\left( {p -} \right)},j}{{{Qch}\left( {p +} \right)},j} \right)} - {{Av}\left\lbrack \left( {{Fslope}\left( {p,{ch}} \right)} \right\rbrack \right\rbrack}} \right.}}$

[0279] where

[0280] N is the number of measurements (or experiments)

[0281] Nch is the number of existing channels a is an arbitraryparameter currently set at 1

[0282] Qch(p+), j is the measured Q value of channel j

[0283] when parameter p was increased

[0284] Qch(p−), j is the measured Q value of channel j

[0285] when parameter p was decreased

[0286] In terms of implementation, for each trial multiple fairedexperiments are made. The results of these experiments are then used inthe calculations below (calculated recursively during the trial) toresult in a final function value at the end of each trial. Thesefunctions are derived from the ratio formula for R(p) as outlined above.

[0287] The trial functions are:${{R1}(p)} = {{Nch}{\sum\limits_{{ch} = 1}^{Nch}{{{w1}\left( {p,{ch}} \right)}{{M1}\left( {p,{ch}} \right)}{{c1}({ch})}\quad {where}}}}$${{M1}\left( {p,{ch}} \right)} = {\frac{1}{Nm}{\sum\limits_{j = 1}^{Nm}{\ln \left( \frac{{{Qth}\left( {p +} \right)},j}{{{Qth}\left( {p -} \right)},j} \right)}}}$

[0288] Nm is the number of pairs of experimental results, each pairhaving one result for an increase in parameter p (p+) and one result fora decrease in parameter p (p−)

[0289] Qch(p+), j is the Q value for channel ch in experiment j whenparameter p was increased

[0290] Qch(p−), j is the Q value for channel ch in experiment j when theparameter p was decreased${{V1}({ch})} = {\frac{1}{Nm}{\sum\limits_{j = 1}^{Nm}\left( {\ln \left( \frac{{{Qch}(2)},j}{{{Qch}(1)},j} \right)} \right)^{2}}}$

[0291] Nm is the number of pairs of experimental results, each pairhaving one result for an increase in parameter p (p+) and one result fora decrease in parameter p (p−)

[0292] Qch(2), j is a Q value after experiment j

[0293] Qch(1), j is the other Q value after experiment j.${{W1}\left( {p,{ch}} \right)} = \frac{N\quad m{{{m1}\left( {p,{ch}} \right)}}}{{{V1}({ch})} - \left( {{M1}\left( {p,{ch}} \right)} \right)^{2}}$

[0294] Nm, M1(p,ch), and V1(ch) are as defined above.${{C1}({ch})} = \frac{1}{\left( {\ln \left( {\frac{a}{2N\quad m}{\sum\limits_{i = 1}^{2{Nm}}\left( {{{Qch}(1)},{j + {{Qch}(2)}},j} \right)}} \right)}^{2} \right.}$Qch  (1), j  and  Qch(2), j  are  as  defined  above  and${{CF1}(p)} = \frac{\left( {{R1}(p)} \right)^{2}}{{Nm}{\sum\limits_{{ch} = 1}^{Nch}\frac{\left( {{{c1}({ch})}{{m1}\left( {p,{ch}} \right)}} \right)^{2}}{{{V1}({ch})} - \left( {{m1}\left( {p,{ch}} \right)}^{2} \right.}}}$

[0295] It should be noted that CF1(p) is the estimated signal to noiseratio on the decision and that C1(ch) is the channel weight function.

[0296] As can be seen from the above functions, the effect of eachparameter perturbation (increase or decrease of the parameter) on eachchannel is accounted for and included in the calculations. It should benoted that the above functions countenance multiple experiments perparameter. Thus, a parameter P may be increased and decreased multipletimes and the results of each increase or decrease is accounted for inthe calculations. A parameter P may thus have multiple similarexperiments per trial with each pair of experimental results beingdifferent from the others. Once the above functions have been computedfor a trial, the results for that trial are further manipulated andcombined with the results of previous trials to arrive at a decisionregarding the direction of change for parameter P.

[0297] The results of the trial for parameter P are then combined withthe previous results (in a running total fashion) in the functionsbelow:${{m2}\left( {p,{ch}} \right)} = {\frac{1}{N2}{\sum\limits_{k = 1}^{N2}{{{m1}\left( {p,{ch}} \right)}k}}}$${{V2}({ch})} = {\frac{1}{N2}{\sum\limits_{k = 1}^{N2}{{{V1}({ch})}k}}}$${{W2}\left( {p,{ch}} \right)} = \frac{{NmN2}{{{m2}\left( {p,{ch}} \right)}}}{{{v2}({ch})} - \left( {{m2}\left( {p,{ch}} \right)} \right)^{2}}$${{C2}({ch})} = {\frac{1}{N2}{\sum\limits_{k = 1}^{N2}{{{C1}({ch})}k}}}$

[0298] where

[0299] N2 is the number of previous trials included in the calculation.This is not necessarily the total number of trials to date. As anexample 100 trials may have been performed to date but only the 10 mostrecent ones may be included in the calculation. N2 therefore controlsthe width of a sliding window which determines which trials are to betaken into account.

[0300] Nm is the number of experimental result pairs included in atrial.

[0301] The final ratio calculation is given by:${{R2}(p)} = {\sum\limits_{{ch} = 1}^{Nch}{{{w2}\left( {p,{ch}} \right)}{{m2}\left( {p,{ch}} \right)}{{C2}({ch})}}}$

[0302] If the result is greater than zero (R(p)>0) then the parameter isto be decreased as the result of the trial, otherwise the parameter isto be increased. The signal to noise ratio of the decision is given by:${{CF2}(p)} = \frac{\left( {{R2}(p)} \right)^{2}}{{NmN2}{\sum\limits_{{ch} = 1}^{Nch}\frac{\left( {{{C2}({ch})}{{m2}\left( {p,{ch}} \right)}^{2}} \right.}{{{V2}({ch})} - \left( {{m2}\left( {p,{ch}} \right)} \right)^{2}}}}$

[0303] From the above trial calculations, it can be seen that thetrial/decision history is accounted for in the calculations without theneed for maintaining a large database of previous trials and theirdecisions.

[0304] Channel Addition

[0305] An added feature of the system is its ability to dynamically addor drop channels to the system without interruption to the otherchannels. This in-service wavelength addition/deletion (or ISWAD forshort) is accomplished by gradually adding or deleting a channel's powerfrom the system. The effects of such added or deleted channels isaccounted for in the steady state optimization by similarly graduallyadding or deleting their Q to the system cost function. Stability in thesystem is maintained by setting Q floor thresholds that must bemaintained by all the other channels during the addition/deletion. Ifthese thresholds are passed by the existing channels, then the processis aborted. This way, disruption of service is avoided and theconvenience of ISWAD is, for that particular instance, sacrificed forservice stability and quality.

[0306] To add a channel, the process begins with determining if theconditions are right to attempt an addition. A minimum acceptable Q ofall the existing wavelength is defined as Q min. This is the lowest Qthat a channel may have. If any existing channels have a Q lower than Qmin, a channel cannot be added. Experiments have shown that, as aminimum, Q min≧QAddTh. QAddTh is the minimum that Q min should have anda value of QAddTh=4.541, which corresponds to a BER of about 10⁻¹⁰⁰(after forward error correction), is suitable.

[0307] Once the minimal conditions have been met, the requiredparameters must be determined. This includes the wavelength of thechannel to be added, the transmission power of its neighbouringwavelengths (at its point of entry into the system), and otherperformance measurements for the neighbouring channels. These parameterscan then be used to get the proper parameters for the incoming channel.

[0308] With the required data gathered, the local controller, thecontroller at the point of insertion of addition, is informed of itsincoming channel. The multiplexer at this point of insertion is thenasked to perform a channel power measurement to determine at what powerlevel the incoming channel is to have. The incoming channel should havea power level that is related to the power levels of the other existingchannels. The normal incoming power of the incoming channel should beequal to the average power of all the existing channels as measured inthe previous trials. To provide greater emphasis on the neighbouringchannels, a neighbouring scheme may be used with the power levels of theneighbouring channels having a greater effect on the average channelpower level calculated.

[0309] If such a weighting system is used, one method would be to relatethe weighting coefficient used on a particular channel to the differencebetween the centre frequency of that channel ane the centre frequency ofthe incoming channel. Thus, an existing channel with a centre frequencyclose to the centre frequency of the incoming channel could be given agreater weight and effect than a second existing channel with a centrefrequency that is far from that of the incoming channel. A formula asfollows can be used:${{Normal}\quad {Power}\quad {of}\quad \lambda_{i}} = {\frac{\sum\limits_{j = 1}^{n}{Pj}}{n} = {Pnormal}}$

[0310] where Pj is the power level of channel j in a system with achannels and λ_(i) denotes the incoming channel.

[0311] If a weighting scheme is used, the following equation may beused:${{Normal}\quad {Power}\quad {of}\quad \lambda_{i}} = {\frac{\sum\limits_{j = 1}^{n}{WpjPj}}{n} = {Pnormal}}$

[0312] where Wpj is the weighting coefficient and its value isdetermined by the difference between the centre frequency of Pj and thecentre frequency of the incoming channel.

[0313] When the desired power level of the incoming channel has beendetermined, the preliminary stage is deemed over. The first stage of theprocess involves gradually increasing the power of the incoming channelto the desired power level by specific increments. The power of theincoming channel (measured as the multiplexer single channel EDFA outputpower) is stepped up from zero to Pnormal with a step size of P_(A)_(ddDel) . The increments can be easily phased in by incrementing thepower level at the end of every trial performed for the continuousoptimization. While the phasing in of the new channel is gradual and istimed by the optimization trials, it should be noted that theperformance of the new channel is not to be taken into account whendetermining the system's overall performance. Thus, when calculating thecost function, the weighting coefficient Wc₁ for the new channel beingphased in is zero.

[0314] It should be noted that the phasing in of the new channel can bestopped at any time if the overall system performance is impaired or ifan existing channel is being detrimentally affected. As noted above,Qmin is the minimum value of Q that an existing channel must suppress.Qmin must be greater than or equal to QAddTh or the Q threshold neededto initiate and continue with channel addition. However,

Q _(AddTh) =Q _(ENDLIFE) +Q _(PDL)

[0315] Where

[0316] Q_(ENDLIFE) is the Q value at the end of life system recommendedby a link budget (this can be 3.035)

[0317] Q_(PDL) Is dBQ reserved for the worst short term Q degradationdue to PDL, PMD (polarization mode dispersion), aging, temperaturevariation, and even ISWAD itself. Q_(PDL) is recommended as 1.75 dBQ, or1.51 in linear Q using a base of Q_(ENDLIFE)=3.035. Q_(PDL) isessentially a margin of error or tolerance in the system for unknownfactors whose effects cannot be predicted.

[0318] From the above, if, at any time during the phasing in of the newchannel, any existing channel is determined to have a Q lower then thepredefined QAddTh, then the phasing in or addition is aborted.

[0319] Another possible reason for aborting the channel addition is ifthe phasing in of the new channel is not proceeding properly. As notedabove, the power level of the incoming channel is increased from zero toPnormal in discrete steps. This gradual power level increase, however,cannot proceed indefinitely. A set period of time, Timer Add₁, isspecifically allotted for this part of the procedure. If a power levelof Pnormal has not been achieved in the set period, the weak channelmust be fixed by other means such as human intervention. Alternatively,and this holds true as well for any aborted channel addition, adifferent wavelength or channel can be chosen for addition to thesystem. Thus, any problems in channel addition can lead to either humanintervention (alerted through some alarm system triggered by anomalouscircumstances such as the incoming channels inability to achieveacceptable power levels in a given time period) or a new attempt atadding a different and, hopefully less troublesome channel.

[0320] With the incremental increase of the incoming channel's powerlevel proceeding space, the required equipment settings for this channelmust be set. The transmit laser wavelength, the transmit device level ofthe pulse generator, and the device level of the DGFF (Dynamic GainFlattering Filter) pixel must all be set at their default values. Theoutput power of the demultiplexer EDFA, for this channel, must be set atthe average settings for its neighbouring channels. Thus, if an incomingchannel i has 6 neighbouring channels i−3, i−2, i−1 on one side and i+1,i+2, i+3 on the other, the parameter settings for all these channels areto be found and averaged to arrive at the parameter settings for newchannel i. If, on the other hand, the channel i has no neighbour, thenthe parameter settings are to be left at their default settings. Asnoted above, a first channels' neighbour is defined as a second channelwhose centre frequency is close in value to the first channels' centrefrequency.

[0321] For the incoming channels' DDCM setting, the recommended settingfor SLAT, (system lineup and test) is to be used. If there is norecommended setting for SLAT, then the dispersion measurement must behandle and the DDCM is set as the SLAT.

[0322] This first stage of the channel addition process is consideredover when the Q value for the incoming channel is at least equal to theQ setting for SLAT.

[0323] The second stage of the channel addition process involves finetuning the incoming channel to bring its performance to the level of theexisting channels. To accomplish this, the contribution of the incomingchannel to the cost function is gradually increased until the Q valuefor the incoming channel is fully integrated into the cost functioncalculation. As explained above, the cost function formula is asfollows:${FC} = {\sum\limits_{i = 1}^{Nc}{{Wc}_{i}\left( {\Delta \quad {Qi}} \right)}^{\alpha}}$where ${\Delta \quad Q} = \begin{Bmatrix}{\left( {{Qth} - {Qi}} \right),{{{if}\quad {Qi}} < {Qth}}} \\{0,{{{if}\quad {Qi}} \geq {Qth}}}\end{Bmatrix}$

[0324] Nc=number of channels in the system

[0325] Wc₁=channel weighting coefficient for channel i

[0326] Qth=Q threshold value

[0327] Q_(i)=Q value for channel i

[0328] α=adjustable power factor

[0329] The gradual increase in contribution of the incoming channels' Qvalue to the cost function is effected by increasing its Wc or channelweighting coefficient from 0 to 1 by fixed increments. Thus, forincoming channel i, its channel weighting coefficient is given by

Wc ₁ =Wc ₁ +ΔWc

[0330] where ΔWc is a fixed value.

[0331] The increments are applied to the weighting coefficient on atrial based rate. This means that, initially, Wc_(i) has a value of 0and at every trial its value is increased by ΔWc. Thus, at the 5^(th)trial after the incoming channel is introduced, Wc₁ will have a value of5ΔWc. This continues until Wc₁ has a value of 1.

[0332] It should be noted that the gradual introduction of the incomingchannel's Q will be halted if something untoward occurs. One possibleoccurrence is the degradation of an existing channel's Q value. Eachexisting channel's Q value is maintained and if a channel's Q valuedrops below a specified threshold (such as Q_(ENDLIFE)) then theincrease in the incoming channel's Wc₁ value stops. While the drop in anexisting channel's Q value may not be due to the introduction of theincoming channel, this may be a contributing factor.

[0333] In addition to the gradual increase in the incoming channels' Wc₁value, its parameters are not to be included in the optimizationexperiments until Wc₁=1. In other words, its parameters are not to beincluded until the incoming channel's Q value is a fully functional andcontributing to the cost function. Also, the parameters for the incomingchannel are not to be included in the sorting, processing, or decisionmaking functions until the second stage of the channel addition process.

[0334] Furthermore, the Q value for the incoming channel is not toincluded in the determination of the lowest Q value in the system untilthe Q value for the incoming channel is greater than or equal toQ_(Addth). This second stage of the channel addition process will beconsidered over when the incoming channel's channel weightingcoefficient (Wc₁) equals 1 and when the incoming channel's Q value is atleast equal to Q_(Adddth). In other words, the second stage is declaredover when the incoming channel fully contributes to the cost functionand when the incoming channel passes the Q_(Addth) level.

[0335] Similar to the first stage of the channel addition process, ifthe requirements of the second stage are not fulfilled in a set amountof time, an alarm is triggered and extraordinary measures need to betaken. Thus, if stage 2 is not complete after a specific periodTimer_(Add2) or due to an abortion of the procedure, human interventionto fix the weak incoming channel is required. Alternatively, a newchannel may be chosen for the next channel addition if the second stageis still incomplete.

[0336] Once the second stage in the addition process is finished, theincoming channel becomes an existing channel and its parameters and Qvalue become available to all the calculations and functions utilized inthe continuous optimization.

[0337] To summarize the steps in the channel addition process, FIG. 7 isa flowchart detailing these various steps and their steps. Step 300 isthat of first requesting that a channel be added. This request is madeto system controller and it initiates the rest of the process. Step 310is that of determining the required parameters for the incoming channel.This includes the power level it should have at the end of the processand, as noted above, this power level is based on the power level of theother channels. Step 315 is to set the proper parameters for the devicesbeing used. This includes setting the proper wavelength for the transitlaser and the proper output power setting for the demultiplexer. Afterthis, step 320 tests to determine if the conditions are acceptable for achannel addition. This test may involve testing if the Q values for allexisting channels are above a predetermined threshold. If this test isnot passed, then step 330 aborts the channel addition process and eithera new channel is chosen to be added (step 350) or the weak incomingchannel can be fixed (step 340).

[0338] If the abovenoted test is passed, the incoming channel isintroduced into the system and its power level gradually increased (step370). The first stage of the process (comprising steps 315 to 370) isdeclared complete when the Q value for the incoming channel achieves, asa minimum, a specific threshold. Step 375 tests for this threshold andif it is not met, steps 320-370 are repeated.

[0339] Once the first stage is over, the second stage of the processbegins. Step 380 is of determining if the conditions are correct toinitiate or continue the second stage. If the conditions are notcorrect, then step 390 aborts the channel addition process. Once thechannel addition process in aborted, either the weak incoming channel isfixed by human interventions (step 400) or a new channel is chosen to beadded. If, on the other hand, the stage 2 conditions are correct, thenthe incoming channel is gradually introduced into the cost function.After every increased in the weighting coefficient, step 430 checks ifthe conditions dictate an end to the second stage. If the conditionsstill call for a continuation of the second stage, then steps 380-430are repeated. If the second stage is declared over, then step 440 notesthat the incoming channel is now fully integrated into the system.

[0340] It should be noted that the above process can be repeated to addfurther channels to the system.

[0341] Channel Deletion

[0342] For in service & channel or wavelength deletion, the systemprovides this function by gradually decreasing the outgoing channel'spower level and its contribution to the overall system performance.

[0343] The first of two stages for channel deletion steadily decreasesthe outgoing channel's contribution to the cost function. During thisstage, the parameters of the outgoing channel are removed from thesorting, processing, and decision functions. Then, the weightingcoefficient associated with the outgoing channel's Q value in the costfunction, Wc₁, is decreased by a set amount. This decrease is graduallyeffected with each trial in the optimization process causing a decreasein the coefficient. Thus, if the initial value of the coefficient is Wcand the quantum of the decrease is ΔWc_(i), then after 5 trials, thevalue of Wc₁ is Wc,-5ΔWc_(i). Mathematically, this relation can beexpressed as:

Wc _(1(x)) =Wci _((n−1)) −ΔWc

[0344] where Wc_(i(x)) is the weighting coefficient at trial x

[0345] Wc_(1(x−1)) is the weighting coefficient at trial (x−1), and

[0346] ΔWc is the predetermined decrease value for the coefficient.

[0347] The coefficient is therefore decreased from its normal value,usually 1, to zero.

[0348] While the above is occurring, the rest of the existing channelsare maintained at their previous performance levels. The Q value foreach of these channels is not to drop by more than Q_(PDL) from itsvalue prior to the channel deletion process. As noted above, Q_(PDL) isdBQ reserved for the worst short term Q degradation due PDL, PMD, aging,temperature variation or channel addition/deletion. In short, Q_(PDL) isthe tolerance allowed for the Q valves. If a Q value for an existingchannel does decrease by more then Q_(PDL), then the decrease in theoutgoing channels' weighting coefficient is either slowed down orhalted.

[0349] Furthermore, as noted above, the outgoing channels' parametersare removed from consideration for all optimization tests, calculations,or functions. Not only that, but the Q value for the outgoing channel isalso removed from any consideration relating to system optimization.After the weighting coefficient for the outgoing channel reaches zero,the first stage is determined to be over.

[0350] The second stage of the deletion process involves decreasing thepower level of the outgoing signal. This is done by gradually decreasingthe outgoing channel's power level by a set value at every trial untilthe power level equals zero and its Q value is, at most, equal toQ_(ENDLIFE). Thus, for every trial subsequent to the first stage of thechannel deletion process, the outgoing channels' power level isdecreased by P_(AddDel) units until the power level equals zero. Again,the same conditions that applied to the existing channels in the firststage of the channel deletion process applies as well during the secondstage. If an existing channels' Q value drops by more than Q_(PDL), thenthe power level decrease is halted or slowed down.

[0351] To summarize the steps involved in the channel detection process,FIG. 8 is a flowchart detailing these steps. As can be seen, the initialstep is to request a channel deletion (step 500). This request isreceived by the controller and it initiates the rest of the sequence.Step 510 is to remove the outgoing channel's parameters from all theoptimization functions, decisions, and calculations. This can be done byeither entering a zero coefficient for the relevant parameter or bymerely removing the parameter from the relevant vector. Step 520 checksto determine if conditions allow for a continuation of the channeldeletion. This condition, that the lowest Q value of the existingchannels does not decrease more than a set amount, ensures that thechannel deletion is not causing undue detrimental effects on the systemor, at the very least, that any detrimental effects are not attributableto the channel deletion. If the condition in step 520 is not met, thatthe lowest Q value of the existing channels has dropped by more than theallotted amount, then either of steps 530 or 530 is executed. Step 530halts the channels deletion process while step 540 slows the processdown, perhaps by changing the amount by which the relevant setting orcoefficient is decreased.

[0352] To continue the process, if step 520 is answered in the negative,then step 550 is to decrease the weighting coefficient in the costfunction related to the Q value for the outgoing channel. This stepsteadily diminishes the contribution that the outgoing channel's Q valuemakes to the overall cost function. As noted above, instances of thisdecrease only occurs after an experiment or a trial. Furthermore, andagain as noted above, the amount of decrease is predetermined.

[0353] After the coefficient Wc₁ is decreased, then step 560 checks ifthe exit condition to the first stage (comprising steps 520-560) is met.This condition is that the coefficient decreased in step 550 be equal tozero. Once this is met, the Q value for the outgoing channel is nolonger contributing to the system's cost function. If the condition isnot met, then steps 520-560 (stage 1) is repeated until the condition ismet.

[0354] If the condition noted above is met, then stage two of thedeletion process begins. Step 570 again checks if the condition forcontinuing with the deletion process is met. This condition, and itsconsequences if it is not met, is identical to those of the fist stage.If the lowest Q value for an existing channel in the system decreases byan amount larger than a predetermined amount, then either the channeldeletion process is halted (step 530) or the process is slowed down bydecreasing the amount by which the outgoing channel's power level isdiminished (step 540).

[0355] The next step (step 580), if the condition for continuing thedeletion process is met, is to actually lower the outgoing channel'spower level by a set amount. Much like in stage one, every instance ofthis step is executed only after an optimization trial. Step 530, afterdecreasing the power level of the outgoing channel, is to determine ifthe exit conditions for stage two are met. These conditions are that thepower level of the outgoing channel equals zero and that its Q value is,at most, a certain value.

[0356] If the exit conditions are not met, then the second stage (steps570-590) is repeated until the exit conditions are met. The final step,step 600, ends the deletion process.

[0357] Much like the channel addition process, the channel deletionprocess can be repeated to delete more than one channel.

[0358] It should be noted for clarity that the above channeladdition/deletion processes does not relate to dynamic addition/deletionof specific channels as found in optical add/drop multiplexers. Add/dropin this document refers to adding and deleting or decreasingtransmission capacity in the system and not specific transmission links.Thus, if the system is operating with ten 10 Gbit transmission trunks,any one of these trunks can be activated or deactivated to expand orcontract the transmission capacity of the system. To further clarify theabove, adding a channel, as the term is used above, is identical toactivating a pre-existing trunk while deleting a channel, as the term isused above, is identical to deactivating a pre-existing trunk.

[0359] The above system is particularly suited for controlling opticalcomponents from a remote location. Optical devices such as DCFFs(dynamic gain flattening filters) can be located at location A while thecontroller can be located in location B. The controller can then adjustthe settings and the performance of the DGFF at location A.

[0360] A person understanding the above-described invention may nowconceive of alternative designs, using the principles described herein.All such designs which fall within the scope of the claims appendedhereto are considered to be part of the present invention.

We claim:
 1. An optical transmission system for transmitting a pluralityof optical signals, said system comprising: a plurality of transmittermodules each producing at least one optical signal; a multiplexer modulefor multiplexing said plurality of optical signals on to a singleoptical transmitting medium, said multiplexer receiving said pluralityof optical signals from said transmitter modules; a plurality ofreceiver modules each receiver module receiving at least one opticalsignal; a plurality of optical network elements, said elements beingpositioned between said multiplexer module and at least one of saidreceiver modules; and a global controller module for controllingperformance characteristics and functions of system elements chosen fromthe group comprising: said transmitter modules; said multiplexermodules; said receiver modules; and said optical network elementswherein said global controller module receives data from at least one ofsaid system elements; and said global controller continuously optimizessaid system by changing said characteristics and functions of saidsystem elements based on said data.
 2. A system as in claim 1 whereinsaid optical network elements are chosen from a group comprising:optical amplifiers; optical cross-connects; optical filters; dispersioncompensation modules; optical add/drop multiplexers; dynamic gainflattening filters; and demultiplexer module.
 3. A system as in claim 1wherein at least one of said network elements is equipped with a localcontroller, said local controller controlling at least one performancecharacteristic based on input from said global controller module.
 4. Asystem as in claim 1 wherein said global controller module optimizes thesystem by executing the following method: a) gathering performance datafrom at least two of each of said system elements; b) calculating aperformance value for each optical signal based on said performancedata; c) determining which optical signal has the minimum performancevalue; d) determining which performance characteristics affect saidminimum performance value; e) determining how a specific change in saidperformance characteristics affects said minimum performance value; f)in the event a specific change increases said minimum performance value,implementing said specific change in said performance characteristics;and g) repeating steps a)-f) after implementing a change in saidperformance characteristics.
 5. An optical transmission system fortransmitting at least one optical signal from a transmitting end to areceiving end, said system comprising: at least one transmitter moduleat the transmitting end, said at least one transmitter moduletransmitting said at least one optical signal; at least one receivermodule at the receiving end, said at least one receiver module receivingsaid at least one optical signal; a plurality of optical networkelements between said at least one transmitter module and said at leastone receiver module, at least one of said elements being a receivingelement receiving said at least one optical signal from said at leastone transmitter module, at least one of said elements being atransmitting element transmitting said at least one optical signal tosaid at least one receiver module; and a controller module controllingsaid plurality of optical network elements wherein said controllerreceives data from said optical network elements and optimizes theperformance of said transmission system by continuously modifyingperformance characteristics of said network elements based on said data.6. A system as in claim 5 wherein said network elements are chosen froma group comprising: optical multiplexers; optical demultiplexers;optical amplifiers; optical cross connects; optical filters; dispersioncompensation modules; and optical add/drop multiplexers.
 7. A method ofoptimizing the performance of an optical transmission system having aglobal controller controlling a plurality of optical network elements,said method comprising; a) gathering performance data from at least twosaid optical network elements; b) calculating a system performance valuebased on said performance data of multiple optical signals; c)momentarily changing multiple parameters of said system; d) in the eventa specific momentary change increases said system performance value,implementing a corresponding specific change in said parameters; and e)repeating steps a)-d) after implementing a change in said parameters. 8.A method of optimizing an optical communications system having multiplecomponents and multiple controllable parameters, the method comprising:a) choosing at least one of the multiple parameters to test based on ahistory of results of previous tests; b) temporarily changing the chosenat least one parameter by a first predetermined amount; c) determiningan effect of the change of step b) on the performance of the system; d)determining which action is to be taken relative to the chosen at leastone parameter based on the history of results of previous tests, theaction being chosen from a group comprising: increasing the chosen atleast one parameter; decreasing the chosen at least one parameter; andleaving the chosen at least one parameter at its current setting.
 9. Amethod as in claim 8 wherein step a) comprises: a1) determining asorting value for each of the multiple controllable parameters; a2)sorting the sorting values in order of their magnitude; and a3) choosingthe n parameters from the n sorted values as the chosen at least oneparameter.
 10. A method of optimizing an optical communications systemhaving multiple components and multiple controllable parameters, saidcontrollable parameters affecting at least one transmission channel insaid communications system, the method comprising: a) temporarilyincreasing a controllable test parameter by a first predetermined amountfrom a base setting, said test parameter being one of said controllableparameters; b) determining an effect of the increase of step a) on theperformance of the system; c) temporarily decreasing the controllabletest parameter by a second predetermined amount from the base setting;d) determining an effect of the decrease of step c) on the performanceof the system; e) determining if said test parameter is to be increasedor decreased based at least on said effects determined in steps b) andd); f) implementing an increase or a decrease in said test parameterbased on results of step e); and g) repeating steps a)-f) using theincreased or decreased test parameter as a new base.
 11. A method as inclaim 10 further including the step of: h) repeating steps a)-g) foreach of said controllable parameters.
 12. A method as in claim 11wherein multiple instances of said method are being executed inparallel.
 13. A method as in claim 10 wherein step e) includesdetermining if said test parameter is to be increased or decreased basedon a history of previous increases and decreases of said test parameter.14. An optimization system for optimizing an optical communicationssystem, said communications system having multiple components andmultiple controllable parameters, the optimization system comprising:means for temporarily increasing at least one of said controllableparameters from a base setting; means for temporarily decreasing atleast one of said controllable parameters from a base setting; means fordetermining if an increase or a decrease in said at least one of saidcontrollable parameters improves a performance measurement of saidcommunications system; and means for implementing an increase or adecrease in said at least one of said controllable parameters such thatsaid at least one of said controllable parameters is changed to form anew base setting.
 15. An article of manufacture comprising: a computerreadable and executable code, said code comprising computer instructionsfor optimizing an optical communications system having multiplecomponents and multiple controllable parameters, said controllableparameters affecting at least one transmission channel in saidcommunications system, the instructions comprising: a) temporarilyincreasing a controllable test parameter by a first predetermined amountfrom a base setting, said test parameter being one of said controllableparameters; b) determining an effect of the increase of step a) on theperformance of the system; c) temporarily decreasing the controllabletest parameter by a second predetermined amount from the base setting;d) determining an effect of the decrease of step c) on the performanceof the system; e) determining if said test parameter is to be increasedor decreased based at least on said effects determined in steps b) andd); f) implementing an increase or a decrease in said test parameterbased on results of step e); and g) repeating steps a)-f) using theincreased or decreased test parameter as a new base.
 16. An article ofmanufacture as in claim 15 wherein said instructions further comprise:repeating steps a)-g) for each of said controllable parameters.
 17. Anarticle of manufacture as in claim 16 wherein said instructions allowfor multiple instances of said instructions to be executed in parallel.18. An article of manufacture as in claim 15 wherein said instructionsfurther comprising the step determining if said test parameter is to beincreased or decreased based on a history of previous increases anddecreases of said test parameter.
 19. A method of activating additionaltransmission capacity in an optical communications system, saidadditional capacity comprising at least one incoming optical channel,said method comprising: a) determining if operating conditions in saidcommunications system are conducive to an addition of an incomingoptical channel; b) if operating conditions are conducive to a channeladdition, increasing a power level of said incoming channel; and c)increasing a contribution of said incoming channel to an overall systemperformance measurement.
 20. A method as in claim 19 wherein step c)comprises increasing a coefficient associated with said incoming opticalchannel in a calculation which determines said overall systemperformance measurement.
 21. A method as in claim 20 wherein saidcoefficient is increased by a second predetermined amount.
 22. Anarticle of manufacture comprising: computer readable media containingcomputer readable and executable code comprising instructions for amethod of activating additional transmission capacity in a opticalcommunications system, said additional capacity comprising at least oneincoming optical channel, said method comprising: a) determining ifoperating conditions in said communications system are conducive to anaddition of an incoming optical channel; b) if operating conditions areconducive to a channel addition, increasing a power level of saidincoming channel; and c) a contribution of said incoming channel to anoverall system performance measurement.
 23. An article of manufacture asin claim 22 step c) comprises increasing a coefficient associated withsaid incoming optical channel in a calculation which determines saidoverall system performance measurement.
 24. A method of deactivatingtransmission capacity in an optical communications system, saidtransmission capacity comprising at least one optical channel, saidmethod comprising: a) determining if operating conditions are conduciveto a deactivation of an optical channel; b) if conditions are conduciveto a deactivation of an optical channel, decreasing a contribution of anoutgoing channel to an overall system performance measurement; and c)decreasing a power level of said outgoing channel.
 25. A method as inclaim 24 wherein step c) is initiated after step b) is initiated.
 26. Amethod as in claim 24 wherein in step b) said contribution is decreasedby decreasing a coefficient associated with said outgoing channel by aspecific amount, said coefficient being used in a calculation whichdetermines said overall system performance measurement.
 27. An articleof manufacture comprising: computer readable media containing computerreadable and executable code comprising instructions for deactivatingtransmission capacity in an optical communications system, saidtransmission capacity comprising at least one optical channel, saidinstructions comprising: a) determining if operating conditions areconducive to a deactivation of an optical channel; b) if conditions areconducive to a deactivation of an optical channel, decreasing acontribution of an outgoing channel to an overall system performancemeasurement; and c) decreasing a power level of said outgoing channel.28. An article of manufacture as in claim 27 wherein in step c) isinitiated after step b) is initiated.
 29. An article of manufacture asin claim 30 wherein in step b) said contribution is decreased bydecreasing a coefficient associated with said outgoing channel by aspecific amount, said coefficient being used in a calculation whichdetermines said overall system performance measurement.
 30. A method ofactivating additional transmission capacity in an optical communicationssystem, said additional capacity comprising at least one incomingoptical channel, said method comprising: a) determining parametersettings for equipment said communications system for adding oneincoming channel; b) determining if operating conditions in saidcommunications system are conducive to an addition of an incomingoptical channel; c) activating said incoming channel if operatingconditions are conducive to a channel addition; d) increasing a powerlevel of said incoming channel; and e) optimizing the communicationssystem while said power level is being increased.
 31. A method as inclaim 34 wherein step e) is accomplished by experimenting parameters ofsaid communications system to determine which change in parameters willincrease a system performance value, said system performance value beingbased on performance values of existing channels in said communicationssystem.
 32. A method of optimizing an optical communications systemafter adding additional transmission capacity, said method comprising:a) increasing a contribution of an incoming channel to a overall systemperformance measurement; b) experimenting with parameters of said systemto increase said system performance measurement; and c) repeating stepsa)-b) until said incoming channel is a full component of said systemperformance measurement.
 33. A method as in claim 32 wherein in step a)said contribution is increased by a predetermined amount.
 34. A methodas in claim 32 wherein said system performance measurement is based onperformance values of existing channels in said communications system.35. A method of assessing an overall performance of an opticalcommunications system, said system having multiple parameters andmultiple channels, the method comprising: a) gathering performance datafor said multiple channels; b) calculating a cost function based on saidperformance data; and c) determining if said cost function exceeds apredetermined threshold.
 36. A method as in claim 35 wherein said costfunction is based on the lowest valued performance data.
 37. A method asin claim 35 wherein said multiple parameters are adjusted based on avalue of said cost function.
 38. A method as in claim 35 wherein anincoming channel is added to said system and a contribution ofperformance data from said incoming channels is added to said costfunction.
 39. A method as in claim 38 wherein said contribution of saidperformance data from said incoming channel is gradually added to saidcost function.
 40. A method as in claim 35 wherein an outgoing channelis removed from said system and a contribution of performance data fromsaid outgoing channel is removed from said cost function.
 41. A methodas in claim 40 wherein said contribution of said performance data fromsaid outgoing channel is gradually removed from said cost function. 42.A method of increasing performance of an optical communications networkhaving multiple channels and multiple adjustable parameters, the methodcomprising: a) gathering performance data measurements for a pluralityof said multiple channels; b) determining an overall performancemeasurement for said system based on said performance data measurements;and c) adjusting selected adjustable parameters to improve said overallperformance measurement for said system.
 43. A method as in claim 48wherein said overall performance measurement is a cost function.
 44. Amethod as in claim 48 wherein an improvement of said overall performanceis obtained by lowering a performance of at least one of said mulitplechannels.
 45. A method of deactivating transmission capacity in anoptical communications systems, said transmission capacity comprising atleast one outgoing optical channel, said method comprising: a)determining if operating conditions are conducive to a deactivation ofan optical channel; b) if conditions are conducive to a deactivation ofan optical channel, decreasing a power level of said outgoing channel;and c) optimizing said communication system.
 47. A method ofdeactivating transmission capacity in an optical communications systems,said transmission capacity comprising at least one outgoing opticalchannel, said method comprising: a) determining if operating conditionsare conducive to a deactivation of an optical channel; b) if conditionsare conducive to a deactivation of an optical channel, decreasing acontribution of an outgoing channel to an overall system performancemeasurement; c) of optimizing said communication system.
 48. A method asin claim 48 wherein in step b) said contribution is decreased bydecreasing a coefficient associated with said outgoing channel by aspecific amount, said coefficient being used in a calculation whichdetermines said overall system performance measurement.